Keep possession 3v1 by always giving the player on the ball two options: support from the sides next to the ball, readjust on every pass, and play one touch whenever the next pass is already on.
Mark a 10 x 10 m square with a disc on each corner. Three attackers stand on three of the four sides and one defender goes inside, with one ball. The attackers keep possession with a maximum of two touches while the defender tries to win it. The two players not on the ball must always be on the two sides next to the ball, never on the side opposite it, so every time the ball moves, the player who was not involved in the pass runs round the corner to the free side. If the defender wins it or it leaves the square, he swaps with the player who lost it. Count consecutive passes, play rounds of about 90 seconds, then progress to one touch.
The 3v1 is the smallest rondo and the first one every academy teaches, and its value is in one idea: the player on the ball should always have two options. Three against one is a big enough overload for young players to succeed, so the ball stays alive long enough for that habit to form.
Played in a square, the geometry does the coaching. Three players and four sides means one side is always empty, and the question is which one. If a supporter stands on the side opposite the ball, the defender only has to stand between them to take that pass away with his body. If both supporters are on the sides next to the ball, the defender can only close one of them, and the other pass is on.
That turns movement off the ball into a rule players can check for themselves. On every pass the triangle turns, and the player who was not involved is suddenly opposite the new ball. He has to run round the corner to the free side, and he has to do it while the pass is travelling, not after it arrives. Move late and the receiver has one option, which against a committed defender means none.
The second lesson is when to play first time. When the next pass is already on, one touch keeps the defender a step behind. When it is not, a touch across the body draws the defender towards the ball, which opens the other lane. FIFA's version of this practice asks players to recognise exactly that difference.
Keep the square honest at around ten metres. Much bigger and the defender cannot pressure anything; much smaller and young players cannot control the ball in time to think.
Save it to your private drills, then change the animation, adjust positions, swap equipment, or drop it into a session block. Or start from a blank pitch and build your own.